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GAS PROTECTION SYSTEMSVISQUEEN RADON MEMBRANEINSTALLATION & JOINTINGInstallationVisqueen Radon Gas Membrane andancillary components must be installedin accordance with the recommendationsof Building Research EstablishmentBRE 414 "Protective measures forhousing on gas contaminated land" andCIRIA C665 “Assessing risks posed byhazardous ground gases to buildings”,NHBC guidelines and the CharteredInstitute of Environmental Health GroundGas Handbook. The product is notintended for use where there is the riskof hydrostatic pressure.The membrane should be installed ona compacted sand blinding layer orsmooth concrete float finish allowingadequate overlap for jointing betweenthe sheets and avoiding bridging (i.e.areas of unsupported membrane). Inareas where high levels of unsupportedmembrane occur it is recommendedthat Visqueen Pre Applied Membraneis used. To avoid slip or shear planesand high compressive loadings it is notrecommended to take the membranethrough the wall. In order to provide acontinuous barrier across the cavityVisqueen Zedex CPT DPC should betaken through the blockwork andincorporated below the damp proofcourse cavity tray in the outer leaf.Laps can be joined together by eitherusing the Visqueen Gas Barrier JointingSystem or welded by our specialist onsitecontractors.If the membrane is punctured orperforated then a patch of material withidentical thickness should be lappedat least 150mm beyond the limits ofthe puncture and bonded with VisqueenDouble Sided Jointing Tape and sealedwith Visqueen Single Sided Girth Tape.Alternatively a patch can be formedusing Visqueen Detailing Strip and lappedat least 150mm beyond the limits of thepuncture. External and internal cornersshould be round and reinforced withVisqueen Detailing Strip. Where this isnot possible and the three dimensionalshapes are complex it is recommendeda preformed unit is used.CoveringVisqueen Radon Membrane should becovered by a protective layer as soon aspossible after installation. Care should betaken to ensure that the membrane is notpunctured, stretched or displaced whenapplying a screed or final floor covering.A minimum thickness of 50mm screed isrecommended. When reinforced concreteis to be laid over the barrier the wirereinforcements and spacers must beprevented from contacting the barrier.It is recommended that the barrieris covered with Visqueen ProtectionBoards or screed before positioningthe reinforcement. When underfloorheating is being installed, it isrecommended that the barrier ispositioned between the blinded hardcoreand insulation. This will protect theinsulation from moisture and avoid anyrisk of overheating the membrane.Storage and HandlingVisqueen Radon Gas Barrier is classifiedas non-hazardous when used inaccordance with the relevant Code ofPractice (CP 102:1973). The product ischemically inert and is not affected byacids and alkalis that may be presentin the sub-soils. The material is notrecommended for uses where it willbe exposed to long periods of outdoorweathering as exposure to ultravioletlight will embrittle the product.Weathering will not occur when themembrane is installed in accordance withCP 102:1973. Care should be taken toavoid accidental damage when handlingthe membrane on site. When the weatheris cold all jointing tapes should be keptin a warm and dry place until needed.Installation is not recommendedbelow 5°C.sealing method around universal column penetration(SLAB JUNCTIONS ONLY) (rad - 19)IMPORTANTFor lapping, jointing and puncturerepair, please see ourInstallation section P83.A full technical datasheet isavailable onlinewww.visqueenbuilding.co.uk/gas48